The present invention relates to a vertical axis windmill and especially to a vertical axis windmill which makes it possible to form a number of shaft-installation sections with support frames in which a plurality of blades are mounted in multi-levels on a vertical main shaft to increase a wind receiving rate thereby providing an increased wind receiving area and revolution efficiency with low installation cost and a lot of total electric power generation amount per a certain area.
A known vertical axis windmill for a wind power generator comprises a plurality of vertical blades around a vertical main shaft. However, when one of the blades is subjected to wind, the other is subjected to turbulence and to decreased turning force, so that low torque makes it impossible for such a vertical axis windmill to be used practically. The vertical axis windmill revolves at high speed even at gentle wind, but reduced number of blades causes smaller wind-receiving area, while increased number of blades is likely to produce turbulence under high speed wind.